Open Outbreak

Cholera

Also known as: Vibrio cholerae, O1, O139, V. cholerae

Cholera is an acute diarrhoeal disease caused by certain strains of the bacterium Vibrio cholerae, mainly O1 and O139. People usually get it by swallowing water or food contaminated with human waste containing the bacteria. It is closely linked to unsafe water, poor sanitation, displacement, conflict, flooding, and weak access to care. Symptoms can start quickly, from about 12 hours to 5 days after exposure. Many infections are mild or have no symptoms, but severe cases can cause sudden, profuse watery diarrhoea, vomiting, rapid dehydration, shock, and death within hours if treatment is delayed. The main treatment is prompt rehydration, especially oral rehydration solution, with intravenous fluids for severe dehydration; antibiotics can shorten illness in selected severe cases. Oral cholera vaccines exist and are used to help control outbreaks, but they do not replace safe water, sanitation, hygiene, and rapid treatment. WHO reported continued multi-country surges in 2025, showing that cholera remains a major global public-health threat.

Key facts

TransmissionMainly fecal-oral spread through contaminated water or food; risk rises where water, sanitation, hygiene, and safe food handling are poor.
IncubationAbout 12 hours to 5 days after exposure.
Case fatalityUnknown as a single global constant. WHO reported that in severe untreated disease death can occur within hours; outbreak CFR varies widely by setting. Recent WHO DON reports included 0.7% in Mozambique in 2023, 3.9% in Angola in 2025, and more than 1% in several countries during 2025.
Reproduction numberunknown
VaccineOral cholera vaccines are available and used for outbreak response and prevention in at-risk settings.
TreatmentPrompt rehydration with oral rehydration solution; intravenous fluids for severe dehydration; antibiotics for selected severe cases can shorten illness.
ReservoirHumans are the main outbreak reservoir; the bacterium also persists in aquatic environments.
Endemic regionsEndemic in more than 50 countries, with repeated outbreaks reported especially in parts of Africa and Asia, and occasional resurgence elsewhere including the Caribbean and Middle East.

Transmission

Cholera spreads mainly through the fecal-oral route. In plain English, that means people swallow the bacteria in water or food contaminated with human waste. WHO says this happens most often where there is poor access to clean water, sanitation, and hygiene. Outbreaks are more likely during conflict, displacement, flooding, and other disruptions that damage water and sewage systems. The disease has a short incubation period, usually about 12 hours to 5 days, so outbreaks can grow quickly when conditions are bad. Person-to-person spread is not usually the main driver in the way it is for airborne infections; instead, shared contaminated water and food are the key route. The strains most linked to epidemic cholera are Vibrio cholerae O1 and O139. Because many infected people have mild symptoms or none at all, contamination can continue unnoticed if water safety and sanitation are weak.

Symptoms and severity

Cholera can range from no symptoms at all to a medical emergency. WHO says most people have no symptoms or only mild to moderate illness. When disease is severe, the classic picture is sudden, very large-volume watery diarrhoea, often with vomiting. This can cause dangerous dehydration and salt loss within hours. People may become very thirsty, weak, dizzy, or confused, with sunken eyes and signs of shock. Severe untreated cholera can be fatal very quickly. WHO’s 2023 global update said about 20% of ill people develop acute watery diarrhoea with severe dehydration and are at risk of death. How deadly an outbreak is depends a lot on access to rapid treatment. Recent WHO outbreak notices show this clearly: Mozambique reported a CFR of 0.7% in 2023, while Angola reported 3.9% in 2025, and WHO noted that several countries in 2025 were still above 1%, suggesting delays in care and gaps in case management.

Treatment and vaccines

The most important treatment is fast replacement of water and salts. WHO says cholera is usually easy to treat if care is reached in time, especially with oral rehydration solution. People with severe dehydration may need intravenous fluids urgently. Antibiotics are not the first or only treatment, but in selected severe cases they can shorten diarrhoea and reduce how long bacteria are shed. The 2012 Lancet review also describes rehydration as the core of care and notes that antibiotics have a supporting role. Vaccines are available. WHO uses oral cholera vaccines in outbreak response and for people living in high-risk settings. These vaccines help reduce illness and help control spread, but they are not a complete fix. They do not replace safe drinking water, sanitation, hygiene, surveillance, and rapid treatment access. In recent years WHO has repeatedly highlighted that strong public-health basics are still the main protection against large outbreaks and deaths.

Where it occurs

Cholera is not confined to one region. The Lancet review says it is endemic in more than 50 countries and can also cause large epidemics. WHO’s recent notices show ongoing transmission across several world regions, especially where communities face unsafe water, poor sanitation, overcrowding, poverty, conflict, or climate-related shocks. Recent WHO reports have described outbreaks or surges in countries including Angola, the Democratic Republic of the Congo, Mozambique, Malawi, Haiti, Lebanon, Somalia, Pakistan, and others. In some places cholera is seasonal, often worsening during rainy periods or after floods. In others it can reappear after years of low reporting when infrastructure breaks down. The bacterium is closely tied to aquatic environments, but large human outbreaks are driven by failures in water and sanitation systems. So the map of risk is shaped less by climate alone than by whether people can get safe water, use sanitation, and reach treatment quickly when watery diarrhoea begins.

Recent history

On this site’s archive, cholera has 153 recorded historical events, showing how often it returns as a public-health emergency. WHO’s Disease Outbreak News has described a broad global upsurge since 2022. In late 2022, WHO assessed global cholera risk as very high and noted many simultaneous outbreaks. In early 2023, WHO again warned of a global situation with outbreaks across all six WHO regions. Country reports from that period included Malawi’s deadliest recorded outbreak, active spread in Mozambique, and transmission in the Democratic Republic of the Congo and Haiti. The picture remained serious in 2025. WHO reported 409,222 cholera or acute watery diarrhoea cases and 4,738 deaths from 31 countries between 2025-01-01 and 2025-08-17, with several countries reporting case fatality above 1%. WHO highlighted major outbreaks in Chad, the Democratic Republic of the Congo, South Sudan, and Sudan, while Angola also reported a high fatality ratio in 2025.

What to watch

The main warning signs are not mysterious. First, watch for spread into new provinces or new countries, especially places that have not reported cholera for years. Second, watch for case fatality staying above 1%, which WHO treats as a sign of delayed care or weak case management. Third, look for outbreaks linked to conflict, displacement camps, floods, or damaged water systems, because these conditions can make a local outbreak much harder to control. Fourth, vaccine supply matters: if outbreaks expand faster than oral cholera vaccine can be delivered, control becomes harder. Fifth, antibiotic resistance would be concerning, because antibiotics are useful in selected severe cases, even though rehydration remains the main treatment. Finally, watch whether countries can keep cholera from becoming entrenched after an emergency. Continued transmission through dry seasons, spread beyond usual endemic areas, or repeated resurgence after apparent control would all suggest a more worrying situation.

Related outbreaks

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